Figure 4.

Pattern of responses to the discriminative stimulus for pain relief in the right NAc predicts transition from subacute to chronic pain

(A) Patterns of voxelwise t scores from the contrast DS_pain (SABP_p > SABP_r). Warm colors depict voxels with higher responses in patients with persistent pain, while cool colors depict voxels with higher responses in recovered patients.

(B) The corresponding ROC curve for classifying recovered and persistent-pain patients based on the multivariate classifiers. We report the area under the ROC curve as an estimate of sensitivity and specificity. Associated p values for the comparison to a chance-level ROC curve (i.e., AUC = 0.5) are reported as Bonferroni-corrected p values (corrected for 45 tests, yielding a threshold of p < 0.001). The boxplot additionally shows the probability of being classified as a patient with persistent pain for recovered patients (yellow) and patients with persistent pain at follow up (blue). The hinges of the boxplots represent the first and third quartiles, and the whiskers extend to the last value within 1.5 times the interquartile range. Single data points are shown as black circles. rNAc, right nucleus accumbens; DS, discriminative stimulus; AUC, area under the curve; SABP, patients with subacute back pain; SABPp/r: patients with SABP with persistent pain or recovered pain after 6 months, based on a pain reduction of 20% from baseline to the follow-up assessment.